1. Field of the Invention
This invention relates to load restraints and more particularly to the restraint of preselected particular pallet type loads and is particularly applicable to the preselected pallet type loads carried on various transportation vehicles such as cargo aircraft and in which pallet type loads other than the preselected particular pallet type load may pass over the restraint without damage to the pallet or the restraint.
2. Description of the Prior Art
Various transportation vehicles, such as large cargo carrying aircraft, are often required to carry a variety of loads. It is current practice to have such loads placed on pallets. The pallets are often loaded onto the aircraft from an aft loading door or a side loading door. In general, pairs of spaced apart rails are provided on the aircraft and the spacing between the pairs of rails corresponds to the width of the pallet type loads. Whether loaded from a rear door or from a side door, the pallets must be able to move on the rails in the longitudinal direction, that is, in the fore and aft directions during the loading and unloading of the pallets from the aircraft.
The rails as may be installed in an aircraft run the longitudinal length of the cargo area of the aircraft and for each width of the pallets the corresponding rails are, in general, equally spaced from the centerline of the aircraft.
The standardized pallet sizes are specified in the NAS 3610 Cargo Unit Load Devices Specification and the teaching and technology thereof are incorporated herein by reference. Thus, the width of the pallets may be, for example, eight feet, ten feet, twelve feet, and the like. The aircraft may have pairs of rails corresponding to each specified width so that the aircraft may have the capability of carrying, on the same flight, a large variety of cargos mounted on a variety of the specified width pallets. Cargo restraints may be mounted on or adjacent to the rails for each width of pallets to restrain the pallets from movement during transportation from one location to another. Generally, the movement of the pallets to be restrained is movement fore and aft, movement transverse to the fore and aft and movement in a vertical direction. Consequently, in loading and unloading the pallets, the larger width pallets or other loads must pass over the restraints mounted in the aircraft as utilized on the smaller width pallets. For efficiency it is desired that the restraints be fixed on the rails in a desired longitudinal spaced array corresponding to the longitudinal spacing of pockets or other attachment locations on each of the different pallets. Therefore, the restraints for all except the widest widths of pallets may be overriden during loading and unloading of pallets. If the restraints are removable, considerable time is wasted in installing and removing the restraints in order to allow the pallets to pass thereover. If the restraints are fixed in place, the restraints must be capable of not interfering with any pallets that pass thereover and still be able to engage the pallet which it is designed to restrain.
Further, it is often desired in many applications that the plurality of restraints placed to engage opposite sides of the particular pallet when free of restraining engagement with the pallet, act as guides for ensuring the linear movement of the particular pallet or other load of the dame width on the rails. The guiding function of the restraints is desired to allow the particular pallet or other such loads of the same width to move freely in the longitudinal directions fore and aft without rotational or twisting movement of the particular pallet or other such loads of the same width about a vertical axis or transverse movement of the pallet, that is, in transverse directions perpendicular to the fore and aft direction in order to insure smooth loading and unloading of the particular pallet.
Overridable pallet restraints heretofore proposed have not always been capable of fixed mounting on the aircraft as well as both being capable of engaging and restraining a preselected particular sized pallet for which they are designed but also not interfere with other, larger, pallets passing thereover or other loads of the same width as the particular pallets or other loads of the same transverse width. Additionally, such prior art pallet restraints often did not act as guides to enable the pallet to move only in prescribed directions along a pair of spaced apart rails.
Some of the heretofore proposed pallet restraints had the capability of being permanently mounted adjacent the track corresponding to the particular pallet to be restrained and were provided with pawls adapted to be inserted into pockets on the particular pallet to be restrained. The restraints were overrideable by loads of different configurations and/or not exactly aligned. The restraint was selectively spring biased to an upright position when not being overriden by a wider pallet. The larger pallets or other loads engaged the restraint and, while being overriden, the restraint was pivotally moved against the spring tension from an upright position downwardly into a space formed by a frame on which the restraint was mounted to a retracted position. As the larger pallets passed thereover neither the restraint or the larger pallets were damaged during such overriding movement. After the larger pallet had passed over the restraint, the restraint was pivotally moved by the spring force from the retracted position to the upright position. Some of such restraints were also manually moveable from an upright position to the retracted position and had retention means for holding the restraint in the retracted position and the retention means could be manually operated to release the restraint from the retracted position and thus allow the restraint to move under the spring force to the upright position. However, the fixed pawl of such restraints often limited the utility of the restraints in many applications.
Accordingly, It is an object of the present invention to provide an improved overridable cargo restraint.
It is another object of the present invention to provide an improved overridable cargo restraint that does not interfere with cargo pallets passing thereover.
It is another object of the present invention to provide an improved overridable cargo restraint that does not interfere with cargo pallets passing thereover but also restrains a preselected cargo pallet from movements when engaged therewith.
It is yet another object of the present invention to provide an improved overridable cargo restraint that does not interfere with cargo pallets passing thereover but also restrains a preselected cargo pallet for which it is designed to restrain and to prevent movement thereof in multiple directions.
It is another object of the present invention to provide an improved overridable cargo restraint that does not interfere with cargo pallets passing thereover but also restrains the preselected cargo pallet for which it is designed to restrain and to prevent movement thereof in longitudinal fore and aft directions, side directions and vertical directions for the restraint in a first position thereof and to act as a guide to direct the particular pallet in straight, longitudinal directions during the loading and unloading thereof to prevent rotation of the pallet about a vertical axis for the pallet in a second position thereof.
It is another object of the present invention to provide an improved overridable cargo restraint in which the pawl which is utilized to restrain a particular pallet is movable from an engaged position in which the pawl is in the pocket of the particular pallet to a retracted position in which the pawl is retracted into the restraint so as not to interfere with movements of the pallets.